Joe - The big difference from 3.5.0-12 to 3.5.0-13 is the rebase from stable v3.5.2 to v3.5.3. These commits from v3.5.3 jump out at me as possible root cause:
KVM: VMX: Fix KVM_SET_SREGS with big real mode segments
KVM: x86 emulator: fix byte-sized MOVZX/MOVSX
KVM: VMX: Fix ds/es corruption on i386 with preemption
KVM: x86: apply kvmclock offset to guest wall clock time
KVM: PIC: call ack notifiers for irqs that are dropped form irr
Joe - The big difference from 3.5.0-12 to 3.5.0-13 is the rebase from stable v3.5.2 to v3.5.3. These commits from v3.5.3 jump out at me as possible root cause:
KVM: VMX: Fix KVM_SET_SREGS with big real mode segments
KVM: x86 emulator: fix byte-sized MOVZX/MOVSX
KVM: VMX: Fix ds/es corruption on i386 with preemption
KVM: x86: apply kvmclock offset to guest wall clock time
KVM: PIC: call ack notifiers for irqs that are dropped form irr